// SPDX-License-Identifier: GPL-2.0-only
/*
 * Rockchip OTP Driver
 *
 * Copyright (c) 2018 Rockchip Electronics Co. Ltd.
 * Author: Finley Xiao <finley.xiao@rock-chips.com>
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/nvmem-provider.h>
#include <linux/reset.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

/* OTP Register Offsets */
#define OTPC_SBPI_CTRL 0x0020
#define OTPC_SBPI_CMD_VALID_PRE 0x0024
#define OTPC_SBPI_CS_VALID_PRE 0x0028
#define OTPC_SBPI_STATUS 0x002C
#define OTPC_USER_CTRL 0x0100
#define OTPC_USER_ADDR 0x0104
#define OTPC_USER_ENABLE 0x0108
#define OTPC_USER_Q 0x0124
#define OTPC_INT_STATUS 0x0304
#define OTPC_SBPI_CMD0_OFFSET 0x1000
#define OTPC_SBPI_CMD1_OFFSET 0x1004

/* OTP Register bits and masks */
#define OTPC_USER_ADDR_MASK GENMASK(31, 16)
#define OTPC_USE_USER BIT(0)
#define OTPC_USE_USER_MASK GENMASK(16, 16)
#define OTPC_USER_FSM_ENABLE BIT(0)
#define OTPC_USER_FSM_ENABLE_MASK GENMASK(16, 16)
#define OTPC_SBPI_DONE BIT(1)
#define OTPC_USER_DONE BIT(2)

#define SBPI_DAP_ADDR 0x02
#define SBPI_DAP_ADDR_SHIFT 8
#define SBPI_DAP_ADDR_MASK GENMASK(31, 24)
#define SBPI_CMD_VALID_MASK GENMASK(31, 16)
#define SBPI_DAP_CMD_WRF 0xC0
#define SBPI_DAP_REG_ECC 0x3A
#define SBPI_ECC_ENABLE 0x00
#define SBPI_ECC_DISABLE 0x09
#define SBPI_ENABLE BIT(0)
#define SBPI_ENABLE_MASK GENMASK(16, 16)

#define OTPC_TIMEOUT 10000

#define UDELAY_TWO 2
#define UDELAY_FIVE 5

struct rockchip_otp {
    struct device *dev;
    void __iomem *base;
    struct clk_bulk_data *clks;
    int num_clks;
    struct reset_control *rst;
};

/* list of required clocks */
static const char *const rockchip_otp_clocks[] = {
    "otp",
    "apb_pclk",
    "phy",
};

struct rockchip_data {
    int size;
};

static int rockchip_otp_reset(struct rockchip_otp *otp)
{
    int ret;

    ret = reset_control_assert(otp->rst);
    if (ret) {
        dev_err(otp->dev, "failed to assert otp phy %d\n", ret);
        return ret;
    }

    udelay(UDELAY_TWO);

    ret = reset_control_deassert(otp->rst);
    if (ret) {
        dev_err(otp->dev, "failed to deassert otp phy %d\n", ret);
        return ret;
    }

    return 0;
}

static int rockchip_otp_wait_status(struct rockchip_otp *otp, u32 flag)
{
    u32 status = 0;
    int ret;

    ret = readl_poll_timeout_atomic(otp->base + OTPC_INT_STATUS, status, (status & flag), 1, OTPC_TIMEOUT);
    if (ret) {
        return ret;
    }

    /* clean int status */
    writel(flag, otp->base + OTPC_INT_STATUS);

    return 0;
}

static int rockchip_otp_ecc_enable(struct rockchip_otp *otp, bool enable)
{
    int ret = 0;

    writel(SBPI_DAP_ADDR_MASK | (SBPI_DAP_ADDR << SBPI_DAP_ADDR_SHIFT), otp->base + OTPC_SBPI_CTRL);

    writel(SBPI_CMD_VALID_MASK | 0x1, otp->base + OTPC_SBPI_CMD_VALID_PRE);
    writel(SBPI_DAP_CMD_WRF | SBPI_DAP_REG_ECC, otp->base + OTPC_SBPI_CMD0_OFFSET);
    if (enable) {
        writel(SBPI_ECC_ENABLE, otp->base + OTPC_SBPI_CMD1_OFFSET);
    } else {
        writel(SBPI_ECC_DISABLE, otp->base + OTPC_SBPI_CMD1_OFFSET);
    }

    writel(SBPI_ENABLE_MASK | SBPI_ENABLE, otp->base + OTPC_SBPI_CTRL);

    ret = rockchip_otp_wait_status(otp, OTPC_SBPI_DONE);
    if (ret < 0) {
        dev_err(otp->dev, "timeout during ecc_enable\n");
    }

    return ret;
}

static int rockchip_otp_read(void *context, unsigned int offset, void *val, size_t bytes)
{
    struct rockchip_otp *otp = context;
    u8 *buf = val;
    int ret = 0;

    ret = clk_bulk_prepare_enable(otp->num_clks, otp->clks);
    if (ret < 0) {
        dev_err(otp->dev, "failed to prepare/enable clks\n");
        return ret;
    }

    ret = rockchip_otp_reset(otp);
    if (ret) {
        dev_err(otp->dev, "failed to reset otp phy\n");
        goto disable_clks;
    }

    ret = rockchip_otp_ecc_enable(otp, false);
    if (ret < 0) {
        dev_err(otp->dev, "rockchip_otp_ecc_enable err\n");
        goto disable_clks;
    }

    writel(OTPC_USE_USER | OTPC_USE_USER_MASK, otp->base + OTPC_USER_CTRL);
    udelay(UDELAY_FIVE);
    while (bytes--) {
        writel(offset++ | OTPC_USER_ADDR_MASK, otp->base + OTPC_USER_ADDR);
        writel(OTPC_USER_FSM_ENABLE | OTPC_USER_FSM_ENABLE_MASK, otp->base + OTPC_USER_ENABLE);
        ret = rockchip_otp_wait_status(otp, OTPC_USER_DONE);
        if (ret < 0) {
            dev_err(otp->dev, "timeout during read setup\n");
            goto read_end;
        }
        *buf++ = readb(otp->base + OTPC_USER_Q);
    }

read_end:
    writel(0x0 | OTPC_USE_USER_MASK, otp->base + OTPC_USER_CTRL);
disable_clks:
    clk_bulk_disable_unprepare(otp->num_clks, otp->clks);

    return ret;
}

static struct nvmem_config otp_config = {
    .name = "rockchip-otp",
    .owner = THIS_MODULE,
    .read_only = true,
    .stride = 1,
    .word_size = 1,
    .reg_read = rockchip_otp_read,
};

static const struct rockchip_data px30_data = {
    .size = 0x40,
};

static const struct of_device_id rockchip_otp_match[] = {
    {
        .compatible = "rockchip,px30-otp",
        .data = (void *)&px30_data,
    },
    {
        .compatible = "rockchip,rk3308-otp",
        .data = (void *)&px30_data,
    },
    {},
};
MODULE_DEVICE_TABLE(of, rockchip_otp_match);

static int rockchip_otp_probe(struct platform_device *pdev)
{
    struct device *dev = &pdev->dev;
    struct rockchip_otp *otp;
    const struct rockchip_data *data;
    struct nvmem_device *nvmem;
    int ret, i;

    data = of_device_get_match_data(dev);
    if (!data) {
        dev_err(dev, "failed to get match data\n");
        return -EINVAL;
    }

    otp = devm_kzalloc(&pdev->dev, sizeof(struct rockchip_otp), GFP_KERNEL);
    if (!otp) {
        return -ENOMEM;
    }

    otp->dev = dev;
    otp->base = devm_platform_ioremap_resource(pdev, 0);
    if (IS_ERR(otp->base)) {
        return PTR_ERR(otp->base);
    }

    otp->num_clks = ARRAY_SIZE(rockchip_otp_clocks);
    otp->clks = devm_kcalloc(dev, otp->num_clks, sizeof(*otp->clks), GFP_KERNEL);
    if (!otp->clks) {
        return -ENOMEM;
    }

    for (i = 0; i < otp->num_clks; ++i) {
        otp->clks[i].id = rockchip_otp_clocks[i];
    }

    ret = devm_clk_bulk_get(dev, otp->num_clks, otp->clks);
    if (ret) {
        return ret;
    }

    otp->rst = devm_reset_control_get(dev, "phy");
    if (IS_ERR(otp->rst)) {
        return PTR_ERR(otp->rst);
    }

    otp_config.size = data->size;
    otp_config.priv = otp;
    otp_config.dev = dev;
    nvmem = devm_nvmem_register(dev, &otp_config);

    return PTR_ERR_OR_ZERO(nvmem);
}

static struct platform_driver rockchip_otp_driver = {
    .probe = rockchip_otp_probe,
    .driver =
        {
            .name = "rockchip-otp",
            .of_match_table = rockchip_otp_match,
        },
};

static int __init rockchip_otp_init(void)
{
    int ret;

    ret = platform_driver_register(&rockchip_otp_driver);
    if (ret) {
        pr_err("failed to register otp driver\n");
        return ret;
    }

    return 0;
}

static void __exit rockchip_otp_exit(void)
{
    return platform_driver_unregister(&rockchip_otp_driver);
}

subsys_initcall(rockchip_otp_init);
module_exit(rockchip_otp_exit);

MODULE_DESCRIPTION("Rockchip OTP driver");
MODULE_LICENSE("GPL v2");
